US4807835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Spacecraft attitude stabilization system
Assignee: ITHACO Inc PO BOX 6437 ITHACA NEW YORK 14851 A CORP OF NY
•
Filing: 1987-04-10
•
Granted: 1989-02-28
•
Expires: 2007-04-10
Abstract
Abstract The attitude of a spacecraft can be effectively controlled in three axes using the combination of a gravity gradient boom and three electromagnets. The electromagnets are controlled according to a control law that takes into consideration signals from a magnetometer and a signal indicating the orbital angular velocity of the spacecraft. During the acquisition phase of the flight, the gravity gradient boom is not extended and electromagnets are operated according to a control law that only takes into account the output of the magnetometer. After the acquisition phase is complete, the gravity gradient boom is extended and the spacecraft enters the libration phase of the flight. In the libration phase of the flight, electromagnets are controlled according to a control law that takes into account both the output of the magnetometer and a signal which indicates the orbital angular velocity of the spacecraft.
Inventors
- 👤 Robert Z. Fowler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:05
CPC Classifications
B; B64; B64G; B64G1/00; B64G1/22; B64G1/24; B64G1/244
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
121 words
A control system for controlling a spacecraft in both an acquisition phase and in a libration phase of flight comprising: a plurality of electromagnets, means for generating rate signals indicating the rate of change of the Earth's magnetic field in a plurality of directions, means responsive to said rate signals for activating said electromagnets during said acquisition phase, means for generating an orbital signal indicating the orbital angular velocity of said spacecraft, means responsive to both said rate signals and to said orbital angular velocity signal for controlling said spacecraft during said libration phase, whereby the attitude of said space craft is controlled in both the acquisition phase of flight and in the libration phase of flight using the same electromagnets.
Claim 2
Dependent Claim
121 words
A control system for controlling a spacecraft in both an acquisition phase and in a libration phase of flight comprising: a plurality of electromagnets, means for generating rate signals indicating the rate of change of the Earth's magnetic field in a plurality of directions, means responsive to said rate signals for activating said electromagnets during said acquisition phase, means for generating an orbital signal indicating the orbital angular velocity of said spacecraft, means responsive to both said rate signals and to said orbital angular velocity signal for controlling said spacecraft during said libration phase, whereby the attitude of said space craft is controlled in both the acquisition phase of flight and in the libration phase of flight using the same electromagnets.
Claim 3
Dependent Claim
84 words
A control system for controlling the librational motion of a spacecraft comprising: three orthogonally positioned electromagnets, means for generating signals indicating the rate of change of the Earth's magnetic field in each of three orthogonal directions, means for generating an orbital signal indicating the orbital angular velocity of said spacecraft, control means responsive to both said rate signal and to said orbital angular velocity signal for controlling the operation of said electromagnets, whereby the librational motion of said spacecraft is controlled in three axes.
Claim 4
Dependent Claim
84 words
A control system for controlling the librational motion of a spacecraft comprising: three orthogonally positioned electromagnets, means for generating signals indicating the rate of change of the Earth's magnetic field in each of three orthogonal directions, means for generating an orbital signal indicating the orbital angular velocity of said spacecraft, control means responsive to both said rate signal and to said orbital angular velocity signal for controlling the operation of said electromagnets, whereby the librational motion of said spacecraft is controlled in three axes.
Claim 5
Dependent Claim
52 words
The system recited in claim 2 wherein said control means operates according to the following control laws: My=-pg By Mx=-rg (Bx+0.5 Wo Bz) Mz=-yg (Bz-2 Wo Bx) Where: Bz, Bx, and Bz are the differentiated signals My, Mx and Mx are the activating signals, Wo is the orbital rate of the spacecraft
Claim 6
Dependent Claim
22 words
The system recited in claim 2 wherein said electromagnets are also used in the acquisition phase of flight to stabilize said spacecraft.
Claim 7
Dependent Claim
25 words
The system recited in claim 1 wherein said electromagnets are only operated in selected portions of the spacecraft orbit during the libration phase of flight.
Claim 8
Dependent Claim
25 words
The system recited in claim 1 wherein said electromagnets are only operated in selected portions of the spacecraft orbit during the libration phase of flight.
Claim 9
Dependent Claim
18 words
The system recited in claim 1 wherein said electromagnets control the yaw, pitch and roll of said spacecraft.
Claim 10
Dependent Claim
28 words
The system recited in claim 7 wherein electromagnet that controls pitch is activated by the same control law during both the acquisition and the libration phase of flight.
Claim 11
Dependent Claim
41 words
The system recited in claim 2 wherein said electromagnets control the yaw, pitch and roll of said spacecraft and, wherein electromagnet that controls pitch is activated by the same control law during both the acquisition and the libration phase of flight.
References Cited (Backward Citations)
US3061239A
Cited
US3232561A
Cited
US3367605A
Cited
US3429524A
Cited
US3489372A
Cited
US3681583A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-28 | 1992-08-29 | 1993-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-28 | 1996-08-29 | 1997-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-28 | 2000-08-29 | 2001-02-28 | $7700.00 | Window Closed / Lapsed |